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Trie: Fix trie format

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After switching to 16-way tries, trie format ignored unaligned / internal
prefixes and only reported the primary prefix of a trie node.

Fix trie format by showing internal prefixes based on the 'local' bitmask
of a node. Also do basic (intra-node) reconstruction of prefix patterns
by finding common subtrees in 'local' bitmask.

In future, we could improve that by doing inter-node reconstruction, so
prefixes entered as one pattern for a subtree (e.g. 192.168.0.0/18+)
would be reported as such, like with aligned prefixes.
This commit is contained in:
Ondrej Zajicek (work) 2022-02-06 22:53:55 +01:00
parent 5a89edc6fd
commit 24600c642a
2 changed files with 111 additions and 22 deletions
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27
filter/test.conf
View File

@ -479,6 +479,33 @@ prefix set pxs;
bt_assert(1.2.0.0/16 ~ [ 1.0.0.0/8{ 15 , 17 } ]);
bt_assert([ 10.0.0.0/8{ 15 , 17 } ] != [ 11.0.0.0/8{ 15 , 17 } ]);
/* Formatting of prefix sets, some cases are a bit strange */
bt_assert(format([ 0.0.0.0/0 ]) = "[0.0.0.0/0]");
bt_assert(format([ 10.10.0.0/32 ]) = "[10.10.0.0/32{0.0.0.1}]");
bt_assert(format([ 10.10.0.0/17 ]) = "[10.10.0.0/17{0.0.128.0}]");
bt_assert(format([ 10.10.0.0/17{17,19} ]) = "[10.10.0.0/17{0.0.224.0}]"); # 224 = 128+64+32
bt_assert(format([ 10.10.128.0/17{18,19} ]) = "[10.10.128.0/18{0.0.96.0}, 10.10.192.0/18{0.0.96.0}]"); # 96 = 64+32
bt_assert(format([ 10.10.64.0/18- ]) = "[0.0.0.0/0, 0.0.0.0/1{128.0.0.0}, 0.0.0.0/2{64.0.0.0}, 0.0.0.0/3{32.0.0.0}, 10.10.0.0/16{255.255.0.0}, 10.10.0.0/17{0.0.128.0}, 10.10.64.0/18{0.0.64.0}]");
bt_assert(format([ 10.10.64.0/18+ ]) = "[10.10.64.0/18{0.0.96.0}, 10.10.64.0/20{0.0.31.255}, 10.10.80.0/20{0.0.31.255}, 10.10.96.0/20{0.0.31.255}, 10.10.112.0/20{0.0.31.255}]");
bt_assert(format([ 10.10.160.0/19 ]) = "[10.10.160.0/19{0.0.32.0}]");
bt_assert(format([ 10.10.160.0/19{19,22} ]) = "[10.10.160.0/19{0.0.32.0}, 10.10.160.0/20{0.0.28.0}, 10.10.176.0/20{0.0.28.0}]"); # 28 = 16+8+4
bt_assert(format([ 10.10.160.0/19+ ]) = "[10.10.160.0/19{0.0.32.0}, 10.10.160.0/20{0.0.31.255}, 10.10.176.0/20{0.0.31.255}]");
bt_assert(format([ ::/0 ]) = "[::/0]");
bt_assert(format([ 11:22:33:44:55:66:77:88/128 ]) = "[11:22:33:44:55:66:77:88/128{::1}]");
bt_assert(format([ 11:22:33:44::/64 ]) = "[11:22:33:44::/64{0:0:0:1::}]");
bt_assert(format([ 11:22:33:44::/64+ ]) = "[11:22:33:44::/64{::1:ffff:ffff:ffff:ffff}]");
bt_assert(format([ 11:22:33:44::/65 ]) = "[11:22:33:44::/65{::8000:0:0:0}]");
bt_assert(format([ 11:22:33:44::/65{65,67} ]) = "[11:22:33:44::/65{::e000:0:0:0}]"); # e = 8+4+2
bt_assert(format([ 11:22:33:44:8000::/65{66,67} ]) = "[11:22:33:44:8000::/66{::6000:0:0:0}, 11:22:33:44:c000::/66{::6000:0:0:0}]"); # 6 = 4+2
bt_assert(format([ 11:22:33:44:4000::/66- ]) = "[::/0, ::/1{8000::}, ::/2{4000::}, ::/3{2000::}, 11:22:33:44::/64{ffff:ffff:ffff:ffff::}, 11:22:33:44::/65{::8000:0:0:0}, 11:22:33:44:4000::/66{::4000:0:0:0}]");
bt_assert(format([ 11:22:33:44:4000::/66+ ]) = "[11:22:33:44:4000::/66{::6000:0:0:0}, 11:22:33:44:4000::/68{::1fff:ffff:ffff:ffff}, 11:22:33:44:5000::/68{::1fff:ffff:ffff:ffff}, 11:22:33:44:6000::/68{::1fff:ffff:ffff:ffff}, 11:22:33:44:7000::/68{::1fff:ffff:ffff:ffff}]");
bt_assert(format([ 11:22:33:44:c000::/67 ]) = "[11:22:33:44:c000::/67{::2000:0:0:0}]");
bt_assert(format([ 11:22:33:44:c000::/67{67,71} ]) = "[11:22:33:44:c000::/67{::2000:0:0:0}, 11:22:33:44:c000::/68{::1e00:0:0:0}, 11:22:33:44:d000::/68{::1e00:0:0:0}]");
bt_assert(format([ 11:22:33:44:c000::/67+ ]) = "[11:22:33:44:c000::/67{::2000:0:0:0}, 11:22:33:44:c000::/68{::1fff:ffff:ffff:ffff}, 11:22:33:44:d000::/68{::1fff:ffff:ffff:ffff}]");
}
bt_test_suite(t_prefix_set, "Testing prefix sets");

106
filter/trie.c
View File

@ -206,6 +206,19 @@ attach_node(struct f_trie_node *parent, struct f_trie_node *child, int v4)
}
/*
* Internal prefixes of a node a represented by the local bitmask, each bit for
* one prefix. Bit 0 is unused, Bit 1 is for the main prefix of the node,
* remaining bits correspond to subprefixes by this pattern:
*
* 1
* 2 3
* 4 5 6 7
* 8 9 A B C D E F
*
* E.g. for 10.0.0.0/8 node, the 10.64.0.0/10 would be position 5.
*/
/*
* Compute appropriate mask representing prefix px/plen in local bitmask of node
* with prefix length nlen. Assuming that nlen <= plen < (nlen + TRIE_STEP).
@ -244,6 +257,18 @@ trie_amask_to_local(ip_addr px, ip_addr amask, uint nlen)
return local;
}
/*
* Compute a bitmask representing a level of subprefixes (of the same length),
* using specified position as a root. E.g., level 2 from root position 3 would
* be bit positions C-F, returned as bitmask 0xf000.
*/
static inline uint
trie_level_mask(uint pos, uint level)
{
return ((1u << (1u << level)) - 1) << (pos << level);
}
#define GET_ADDR(N,F,X) ((X) ? ipt_from_ip4((N)->v4.F) : ipa_from_ip6((N)->v6.F))
#define SET_ADDR(N,F,X,V) ({ if (X) (N)->v4.F =ipt_to_ip4(V); else (N)->v6.F =ipa_to_ip6(V); })
@ -267,7 +292,7 @@ trie_add_node(struct f_trie *t, uint plen, ip_addr px, uint local, uint l, uint
/* Add all bits for each active level (0x0002 0x000c 0x00f0 0xff00) */
for (uint i = 0; i < TRIE_STEP; i++)
if ((l <= (plen + i)) && ((plen + i) <= h))
local |= ((1u << (1u << i)) - 1) << (1u << i);
local |= trie_level_mask(1, i);
DBG("Insert node %I/%u (%I %x)\n", paddr, plen, amask, local);
while (n)
@ -1036,30 +1061,70 @@ trie_same(const struct f_trie *t1, const struct f_trie *t2)
return trie_node_same6(&t1->root.v6, &t2->root.v6);
}
static void
trie_node_format4(const struct f_trie_node4 *t, buffer *buf)
{
if (t == NULL)
return;
if (ip4_nonzero(t->accept))
buffer_print(buf, "%I4/%d{%I4}, ", t->addr, t->plen, t->accept);
for (uint i = 0; i < (1 << TRIE_STEP); i++)
trie_node_format4(t->c[i], buf);
}
static const u8 log2[16] = {0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3};
static void
trie_node_format6(const struct f_trie_node6 *t, buffer *buf)
trie_node_format(const struct f_trie_node *n, buffer *buf, int v4)
{
if (t == NULL)
if (n == NULL)
return;
if (ip6_nonzero(t->accept))
buffer_print(buf, "%I6/%d{%I6}, ", t->addr, t->plen, t->accept);
if (v4)
{
if (ip4_nonzero(n->v4.accept))
buffer_print(buf, "%I4/%d{%I4}, ", n->v4.addr, n->v4.plen, n->v4.accept);
}
else
{
if (ip6_nonzero(n->v6.accept))
buffer_print(buf, "%I6/%d{%I6}, ", n->v6.addr, n->v6.plen, n->v6.accept);
}
for (uint i = 0; i < (1 << TRIE_STEP); i++)
trie_node_format6(t->c[i], buf);
int nlen = v4 ? n->v4.plen : n->v6.plen;
uint local = v4 ? n->v4.local : n->v6.local;
for (int i = (nlen ? 0 : 1); i < TRIE_STEP; i++)
if (GET_ACCEPT_BIT(n, v4, nlen + i - 1))
local &= ~trie_level_mask(1, i);
for (int pos = 2; local && (pos < (1 << TRIE_STEP)); pos++)
if (local & (1u << pos))
{
int lvl = log2[pos];
int plen = nlen + lvl;
int i;
for (i = 0; lvl + i < TRIE_STEP; i++)
{
uint lmask = trie_level_mask(pos, i);
if ((local & lmask) != lmask)
break;
local &= ~lmask;
}
uint addr_bits = pos & ((1u << lvl) - 1);
uint accept_bits = (1u << i) - 1;
int h = plen + i - 1;
if (v4)
{
ip4_addr addr = ip4_setbits(n->v4.addr, plen - 1, addr_bits);
ip4_addr mask = ip4_setbits(IP4_NONE, h - 1, accept_bits);
buffer_print(buf, "%I4/%d{%I4}, ", addr, plen, mask);
}
else
{
ip6_addr addr = ip6_setbits(n->v6.addr, plen - 1, addr_bits);
ip6_addr mask = ip6_setbits(IP6_NONE, h - 1, accept_bits);
buffer_print(buf, "%I6/%d{%I6}, ", addr, plen, mask);
}
}
for (int i = 0; i < (1 << TRIE_STEP); i++)
trie_node_format(GET_CHILD(n, v4, i), buf, v4);
}
/**
@ -1077,10 +1142,7 @@ trie_format(const struct f_trie *t, buffer *buf)
if (t->zero)
buffer_print(buf, "%I/%d, ", t->ipv4 ? IPA_NONE4 : IPA_NONE6, 0);
if (t->ipv4)
trie_node_format4(&t->root.v4, buf);
else
trie_node_format6(&t->root.v6, buf);
trie_node_format(&t->root, buf, t->ipv4);
if (buf->pos == buf->end)
return;